1. Field of the Invention
The present invention relates generally to golf clubs, and more particularly to adjustable golf clubs.
2. Background of Related Art
A variety of golf clubs exist. In the game of golf, a player swings clubs to strike and propel a ball towards, and eventually into, a hole. The object of the game is to hit the ball into a series of holes, generally eighteen holes, using as few swings, or strokes, as possible.
Golfers have many different swing types. This variety in swing types means that different golfers contact the ball in different ways. Some golfers may contact the ball, for example, while the club face is moving from left to right across the ball. Other golfers may contact the ball while the club face is moving from right to left, up to down, down to up, or various combinations thereof. In addition, some golfers rotate the club face such that it is angled toward the golfer (“closed”) or away from the golfer (“open”). Each of these different swings can impart a different spin and/or flight trajectory to the ball. The ball may “slice” or “hook,” for example, based on the type of swing the golfer uses. These trajectories can be desirable when intended and undesirable when unintended.
Golfers' strokes also tend to change over time. A golfer who previously contacted the ball with the club-face moving from left to right, for example, may modify his swing or stance so that he contacts the ball with the club face moving from right to left. This can have a significant effect on the trajectory of the ball. Again, this can be a desirable effect if the results are intended or an undesirable effect if the results are unintended.
In addition to a golfer's swing, the physical specifications, or inherent characteristics of the club head may also influence trajectory. Three influential characteristics are loft angle, lie angle, and face angle. Since golfers have a wide array of body and swing types, each of these angles should be adjustable to an appropriate value for the desired ball trajectory for each golfer. As shown in FIG. 1a, the loft is the angle between the club face and a vertical line, i.e., the angle of the club face from vertical. As shown in FIG. 1b, the lie is the angle between the hosel axis and the ground plane. As shown in FIG. 1c, the face angle is the angle between the club face and a line perpendicular to the target line. Thus, a club with a larger loft angle will cause the ball to have a higher trajectory, but travel a shorter distance. A club with a more upright lie yields a club face that tilts further upward towards the golfer. Finally, a club with a closed face angle is closed to the target (aimed left of the target for a right handed golfer), while an open face angle yields a club face that is open to the target (aimed right of the target for a right handed golfer).
Traditional golf clubs have predetermined loft, lie, and face angles that are not easily adjustable. Thus, the clubs cannot be easily modified to compensate for issues with a golfer's swing, such as unintended “hook” or “slice,” for example. The clubs also cannot be easily modified to compensate for changes in a golfer's swing. While traditional clubs can be altered slightly, this requires bending the hosel and/or the heel of the club. Such an adjustment requires expensive, precise equipment that must be operated by a trained professional. Moreover, such an adjustment should only be done a few times with each club, as repeated bending can cause metal fatigue, which can lead to failure.
Some adjustable golf clubs are known, however. These clubs can be modified to attempt to compensate for errors or changes in a golfer's swing. For example, as shown in FIG. 2, some clubs have a shaft that is slightly offset from the hosel, i.e., the center axis of the shaft and the center axis of the hosel are not aligned. To adjust the club, the shaft can be rotated with respect to the hosel, which causes the club head and the shaft to change position with respect to one-another. This type of club design, known as a “1-axis of rotation” design, has several disadvantages.
The principal disadvantage is that all three angles discussed above—loft, lie, and face angle—are adjusted at the same time, i.e., none of the angles can be adjusted separately. Moreover, in order to adjust the club, the shaft must be rotated, which rotates the grip. This can be problematic because golfers often use markings on the grip to ensure that their hands are in the proper position with respect to the club head. Many golfers also use asymmetrical grips that should be properly aligned with respect to the club head. When the shaft rotates relative to the club head, therefore, a grip that was properly positioned can become skewed, which can make it difficult for the golfer to properly grip the club and effectively strike the ball.
Additionally, some adjustable clubs require the use of a chart to determine the loft, lie, and face angle that the club is adjusted to. For example, some adjustable clubs have letters and/or numbers printed on their moveable components. To determine the loft, lie, and face angle of these clubs, a golfer must take note of certain letters and/or numbers, and reference a chart that provides the corresponding loft, lie, and face angles. These designs can be inconvenient for the golfer, however, as he or she must take time to review the chart, and must also carry the chart with him or her on the golf course.
What is needed, therefore, is an adjustable golf club that allows one or more of loft, lie, and face angle to be adjusted separately from the other two angles. The club should also be adjustable without requiring the shaft to rotate relative to the club head. Additionally, adjustments should be intuitive to the golfer, and should not require the use of a chart to explain the various settings. It is to such a golf club that embodiments of the present invention are primarily directed.